Investigations have shown that glucagon treatment of the perfused rat liver rapidly elicits a modification of the kinetic properties of hepatic pyruvate kinase. The proposed investigation is to separate and purify various hormonally regulated forms of pyruvate kinase and to study their kinetic properties. Also investigations will be continued to demonstrate a similar glucagon or insulin regulation of other hepatic enzymes catalyzing gluconeogenic and glycolytic reactions. Those enzymes to be studied include glucokinase, glucose-6-phosphatase, phospho fructo kinase, fructose-1,6-diphosphatase and phospho pyruvate carboxy kinase.